This invention relates to a developer collection device of a copying machine, which collects a developer remaining on the surface of a photosensitive drum after an image on the surface of a photosensitive drum is transferred to a copying paper.
A developer collection device of this type comprises a removing mechanism for removing a developer remaining on the surface of a photosensitive drum, a receptacle for receiving the developer so removed, a developer collection box disposed at one end portion of the receptacle, and a spiral blade equipped shaft rotatably and axially movably supported in the receptacle such that the developer removed by the removing mechanism can be conveyed toward the developer collection box.
The developer removed by the removing mechanism is collected during the rotation of a shaft toward one end of the shaft and then into the collection box. In a conventional copying machine, the developer is taken out from the collection box when a predetermined number of copying papers are reached.
When the collection time of the developer is determined by the number of copying papers, an amount of developer removed varies dependent upon the size of the copying paper or the copying dnesity. As a result, even if the same number of copying papers are used, an amount of developer recovered differ. There may occur the cases in which, even when the collection box is filled with developer, the operator is not aware of this fact and tries to continue a copying operation. If the copying machine continues to be operated after the collection box is overflowed with the developer, a force opposite to that acting in a direction of conveyance of the developer is applied to the shaft. When such a force is continuously applied to the shaft, the shaft itself and its drive system or the receptacle is injured or broken. If the rotation of the shaft is blocked by a piled-up developer, the developer is coagulated within the receptacle, thereby presenting a maintenance, post-treatment problem etc.